Abstract
The bending yield strength of the frozen soils decrease with salt concentration. The effects of salt on the yield pressure of the circular plates which modeled the frozen soil walls to be mobilized at the starting and/or arriving portals for the shield machine operation was studied. The bending tests on the circular plates of saline frozen soils were carried out in order to determine an approximate relationship between the yield pressure and salt concentration. On the saline frozen clay, the approximation method which had been confirmed the availability at the non-saline frozen soil agreed satisfactorily with the experiment. However on the saline frozen sand, the experimental values of yield pressure were larger than the estimated ones. The reason was investigated using the caluculation by the finite element method and the shear strength of the saline frozen sand.
